DUBAI/KHOBAR, Oct 1 (Reuters) - Saudi Aramco sharply cut official oil prices for Asian customers in November, the state-run company said on Wednesday in the clearest sign yet the world's largest exporter is trying to compete for crude market share.

The move comes amid calls from some within the Organization of the Petroleum Exporting Countries (OPEC) for action to shore up prices, as international benchmark Brent crude oil has slumped to a two-year low.

But the price cuts on Wednesday indicate Saudi is likely to follow its long-stated policy of supplying enough oil to world markets, while at the same time quietly competing with countries like Iraq and Iran to be the top supplier to fast-growing economies like China.

International benchmark Brent crude oil futures reversed course after the Saudi prices were released, turning negative in late trade. At 1835 GMT they were trading down 0.45 percent at $94.25 a barrel.

"Brent is going down hard," one trader said. "It's going to retrace most of the gains from today on this."

Another trader said the fourth-straight monthly reduction made it appear Saudi Arabia may be trying to start a "price war" with rival producers. Regional oil rival Iran may face a budget deficit due to lower prices and Western sanctions.

Saudi slashed its flagship Arab Light selling price by $1 a barrel versus October to a discount of $1.05 a barrel to the Oman/Dubai average. Traders had been expecting a cut no bigger than 70 cents.

Saudi also cut prices to Europe and the United States by 40 cents a barrel.

Traders are now anticipating a tense OPEC meeting when the group next convenes in Vienna this November, to see if the group can respond to ample supplies coming from the shale oil boom in North America and the recovery in output in Libya, which has pushed oil below $95 a barrel for the first time since 2012.

OPEC STAND-OFF

Gulf OPEC members have so-far argued that oil prices will likely recover in the fourth quarter of this year due to stronger demand. Iran's oil minister has urged OPEC to stop the oil price slide.

But a Reuters poll on Wednesday showed the sharpest downward revision to energy analyst oil price forecasts for two years, posing a challenge to the group as most expect Brent to remain weak into 2015.

Saudi Arabia, as the world's top exporter and holder of the world's largest spare capacity, has said it trimmed its output in August, a move analysts seen as playing its role as the world's swing producer.

But the amount of crude supplied to the market - both domestically and for export - inched up to 9.688 million bpd, compared to around 9.66 million bpd in July, an industry source said last week.

A Reuters survey of OPEC output on Tuesday also showed rising supplies from Saudi Arabia and other members of the group, despite a glut of crude weighing on prices.

OPEC secretary-general Abdullah al-Badri said last month he expected the group to lower its output target when it meets in late November. Other countries, including Iran and Venezuela that generally argue for higher prices, may put pressure on the group to take action.

The tables below show the full FOB prices for November in U.S. dollars. Saudi term crude supplies to the United States are priced as a differential to the Argus Sour Crude Index (ASCI). United States